/**
 * Copyright (c) 2015 The JobX Project
 * <p>
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package com.jobxhub.agent.util;


import com.google.common.base.Joiner;
import com.google.common.collect.Iterators;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * A circular buffer of items of a given length. It will grow up to the give size as items are
 * appended, then it will begin to overwrite older items.
 *
 * @param <T> The type of the item contained.
 */
public class CircularBuffer<T> implements Iterable<T> {

    private final List<T> lines;
    private final int size;
    private int start;

    public CircularBuffer(final int size) {
        this.lines = new ArrayList<T>();
        this.size = size;
        this.start = 0;
    }

    public void append(final T line) {
        if (this.lines.size() < this.size) {
            this.lines.add(line);
        } else {
            this.lines.set(this.start, line);
            this.start = (this.start + 1) % this.size;
        }
    }

    @Override
    public String toString() {
        return "[" + Joiner.on(", ").join(this.lines) + "]";
    }

    @Override
    public Iterator<T> iterator() {
        if (this.start == 0) {
            return this.lines.iterator();
        } else {
            return Iterators.concat(this.lines.subList(this.start, this.lines.size()).iterator(),
                    this.lines.subList(0, this.start).iterator());
        }
    }

    public int getMaxSize() {
        return this.size;
    }

    public int getSize() {
        return this.lines.size();
    }

}